Weak-field magnetic field sensor having etched circuit coils

ABSTRACT

The subject of the invention is a weak-field magnetic sensor with the following features: etched circuit coils are substituted for conventional coil technology. The sensor includes an amorphous core having epoxy bases stacked relative to one another on the top and bottom surfaces thereof. One epoxy base has a coil Y etched thereon. A second epoxy base has a coil X etched thereon. The remaining epoxy base has circular patterns etched thereon. The amorphous core is formed from at least two amorphous thin boards stacked on opposite sides of an epoxy base thin board. The epoxy base thin board has a particular pattern etched thereon and the capacity for vertical conductivity. The coil conductor size and position accuracy is controlled in increments of microns by the etching process. The range of detection errors and the level of reception has no non-uniformities. A thin and small sensor in terms of the structure is therefore enabled. Moreover, the sensor is not easily affected by outside factors such as broken wires. It is also capable of being mass produced.

FIELD OF THE INVENTION

This invention relates to a weak-field magnetic sensor and includesmethods for manufacturing the magnetic sensor. The weak-field magneticsensor of the invention is useful for the detection of magnetism that isgenerated from the earth's natural magnetism and other substances.

BACKGROUND OF THE INVENTION

Generally, the basic components of known magnetic sensors are amagnetization coil and a detection coil. When metal substances are putnear a sensor, the magnetic field changes due to the electric eddycurrent generated for the one side nearest the metal substances. Theabove mentioned change of magnetic field affects detection coil output.This process is utilized to detect magnetism. The magnetic sensor,because of its structure, is not easily affected by heat, light, or thesurface of matters for detection. Moreover, it is possible to make smalland light magnetic sensors.

The weak magnetic sensor of the prior existing technology has includedthe following characteristics: the magnetic sensor has adopted highlypermeable magnetic materials for its core component. The sensor iscomposed of a primary coil and a secondary coil. The primary coil sensesmagnetism while the secondary coil detects the degree of saturation. Thesecondary coil has a magnetic axis in two directions so it can obtainthe vector difference axis. Thus, the magnetic direction of weak-fieldmagnetism can be measured.

In the prior technology, the magnetic materials were processed withprecision. Then, the primary and the secondary coil were made utilizinga known wire coil technology. The wire coil technology was appliedaccording to the positioning accuracy of the copper wires covered withthe insulator. However, some magnetic materials with high permeabilityrequired a specific precision process. Moreover, the need for a separateprimary and secondary coil positioning processes caused the followingproblem: it was difficult to maintain a certain coil pressure as well asevenly maintain the positioning accuracy of coils. Thus, the range ofboth the degree of detection errors and the level of reception becameuncertain. Therefore, it has not been possible to make a thin and smallsensor in terms of the structure. The prior art was easily affected bysurrounding factors such as broken wires.

SUMMARY OF THE INVENTION

The present invention is directed to a weak-field magnetic sensor thatsolves the previously described problem of the prior technology. Coilpositioning technology is not required. The positioning accuracy can becontrolled in increments of microns. There is virtually no unevennessconcerning the range of detection errors and the level of reception. Itis possible to make a thin and small sensor in terms of the structuredisclosed. Moreover, it is not easily affected by outside factors suchas broken wires. It is also capable of being mass produced.

The present invention utilizes materials such as alloys that are notaffected by stress and which allow fewer changes to magneticcharacteristics. It also creates the same advantageous conditions as awire coil environment by utilizing etching technology. The aforesaidinvention is a weak-field magnetic sensor which is characterized by thefollowing features: a certain pattern is etched on an epoxy base thinboard with the capacity for vertical conductivity. Circular patterns areetched on the front and on the back surface of the amorphous thinboards. These amorphous thin boards are stacked on both sides of theabove mentioned epoxy base to form an amorphous core. There are twoother epoxy bases and one other amorphous epoxy base. A coil Y is etchedon one epoxy base while a coil X is etched on the other epoxy base.Circular patterns are etched on the amorphous epoxy base. These twoepoxy bases and the amorphous epoxy base are stacked relative to oneanother on the top surface and on the bottom surface of the aforesaidamorphous core.

In the present invention, it is preferable that the epoxy base is madeof materials that are capable of being etched such as glass epoxy,plastic, etc. It is also preferable to utilize etching process in whichthe conductor width can be controlled in increments of microns. The sameeffect can be achieved with the following magnetic sensor: the magneticsensor utilizes a ring shape core made with the above mentionedamorphous thin board instead of the aforesaid flat board amorphous core.The ring shape core is created by cutting the above mentioned amorphousthin board into rings and etching so that it appears that it had beencoiled with a toroidal core. The usage of the aforesaid invention willbe explained in greater detail hereinafter referring to the charts.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

With the foregoing and other objects, advantages, features of theinvention which will become hereinafter apparent, the nature of theinvention may be more clearly understood by reference to the followingdetailed description of the invention, the appended claims, and to theseveral views illustrated in the attached drawings.

FIG. 1 is an explanatory chart of one assembly production process thatillustrates an example of the amorphous magnetic sensor of the presentinvention, using a flat board core;

FIG. 2 is an explanatory chart of one assembly production process thatillustrates an example of the amorphous magnetic sensor of the presentinvention, using a flat board core;

FIG. 3 is an explanatory chart of one assembly production process thatillustrates an example of the amorphous magnetic sensor of the presentinvention, using a flat board core;

FIG. 4 is an explanatory chart of one assembly production process thatillustrates an example of the amorphous magnetic sensor of the presentinvention, using a flat board core;

FIG. 5 is an explanatory chart of the last assembly production processthat illustrates an example of the amorphous magnetic sensor of thepresent invention, using a flat board core; and

FIG. 6 is a disassembly chart indicating an example of the presentinvention using a ring core.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS. 1 to 5 identify the method of assembly and the completed sensor.

They indicate one illustrative embodiment of the amorphous magneticsensor of the aforesaid invention. The amorphous magnetic sensorindicated in FIGS. 1-5 uses a flat board core. FIG. 6 is a disassembledview showing an alternative embodiment of the present invention with aring core instead of the above indicated flat board core.

In each drawing figure, reference numeral 1 indicates an amorphous thinboard. Reference numeral 2 indicates a thin board glass epoxy basehaving specific conductive patterns etched with the capacity forvertical conductivity. The amorphous thin board 1 is stacked and fixedon both surfaces of the aforesaid epoxy base 2 in advance (see FIG. 1).Next, a stacked board is formed by applying a pressing process asindicated in FIG. 2 . Specific circular patterns 3 are etched in advanceon another amorphous thin board 2. Another amorphous stacked board 4, asindicated in FIG. 3, is established on the aforesaid epoxy base 2 andcorresponds to its conductive patterns. Further, a porous process 13 canbe applied to the amorphous stacked board 4 if necessary.

Then, the amorphous stacked board 4 is set as a core as indicated inFIG. 4. There are two glass epoxy bases 2a and 2b. They have specificconductive patterns etched in advance. These glass epoxy bases arestacked and pressed both on the top surface and on the bottom surfacecorresponding to the etched conductive patterns. Thus, a flat board core5 is formed.

Next, two pieces of the following three components are made alongsidethe flat board amorphous core 5. A conductive pattern 10 for coil X isetched on the glass epoxy base 6 to form coil X as is indicated in FIG.6. A conductive pattern 11 for coil Y is etched on the glass epoxy base7 to form the coil Y. A circular conductive pattern 12 is etched on theamorphous glass epoxy base to form the amorphous coil 12 on base 8. Thecoil X on base 6, the coil Y on base 7, and the amorphous coil 12 onbase 8 are stacked and pressed on both the top surface and on the bottomsurface of the flat board core 5 on the outer sides. Each coil isstacked on the core in the order of coil X on base 6, coil Y on base 7,and then amorphous coil 12 on base 8. Also, each coil X, Y, and 12 isaligned according to the etched conductor patterns of each coil so theyare conductive. Thus, a weak-field magnetic sensor is obtained (see FIG.5).

The etching width of each conductor pattern is on the order of a fewmicrons. It is possible to make an extremely small magnetic sensor withsuch dimensions. Even though a glass epoxy base was used for epoxy bases2, 6, 7, and 8 in this illustrative example, the present inventioncontemplates the use of other materials capable of bearing etchedconductor patterns, such as plastic.

FIGS. 1 to 5 explain the illustrative example utilizing the case of aflat board amorphous core 5. However, an alternative illustrativeembodiment is shown in FIG. 6. It is possible to make the followingmagnetic sensor within the scope of the present invention as follows:the magnetic sensor utilizes a ring shape core that was first made fromthe aforesaid amorphous thin board. The ring shape core 9 is created bycutting the amorphous thin board into rings and then etching the boardso that it appears that it has been coiled with a toroidal core.

As described above, the aforesaid invention includes the followingeffects: the magnetic sensor does not require precise coil positioningtechnology as does the known technology. Thus, the range of detectionerrors and the level of reception has no disturbances. Also, thepositioning and dimensional accuracy can be controlled in increments ofmicrons or less. Moreover, a thin material can be used due to use of theetching process. It is possible to imbed the electronic circuit on thesame material as a driver. Thus, a very thin and small sensor can berealized. Furthermore, it is not easily affected by outside factors suchas broken wires. It is also capable of being mass produced.

Although certain presently preferred embodiments of the invention havebeen described herein, it will be apparent to those skilled in the artto which the invention pertains that variations and modifications of thedescribed embodiment may be made without departing from the spirit andscope of the invention. Accordingly, it is intended that the inventionbe limited only to the extent required by the appended claims and theapplicable rules of law.

I claim:
 1. A weak-field magnetic sensor, comprising:an epoxy base thinboard on which is etched certain pattern, having the capacity forvertical conductivity; at least two amorphous thin boards, each havingfront and back surfaces, and each having circular patterns etched on thefront and the back surfaces, wherein the amorphous thin boards arestacked on both sides of the epoxy base to form an amorphous core; afirst epoxy base on which a coil Y is etched; a second epoxy base onwhich a coil X is etched; and an amorphous epoxy base on which areetched circular patterns; wherein the first and second epoxy bases andthe amorphous epoxy base are stacked relative to one another on the topsurface and on the bottom surface of the aforesaid amorphous core.
 2. Aweak-field magnetic sensor as in claim 1 in which the epoxy base is madeof glass epoxy material capable of bearing etched conductor patterns. 3.A weak-field magnetic sensor as in claim 1 in which the epoxy base ismade of plastic material capable of bearing etched conductor patterns.